A Private Branch Exchange (PBX) or a communication system typically serves a plurality of different types of communication devices such as stations, attendant consoles, printers, terminals, and trunk facilities such as Central Office (C.O.) trunks. The PBX or the system offers the device and trunk facility users access to a variety of call features. Access to these features is dependent on the authorization level of each devices or trunk facility; that is, users are permitted access either to all, some or none of the features. However, a user who is not permitted access to all features may sometimes attempt to circumvent the restriction and, if successful, gain access to unauthorized features.
One example of where restrictions on call features may be present is a hotel. Hotels usually restrict the placement of long-distance cells from guest stations. Each guest station of the hotel PBX is assigned a restriction which prevents the guest from making long-distance calls without going through proper billing facilities. A "clever" guest may sometimes attempt to circumvent the long-distance restriction and place unauthorized long-distance calls that circumvent the billing facilities. The placement of these unauthorized long-distance calls defeats the maintenance of accurate billing records and is costly to the hotel.
Another example of accessing unauthorized PBX features may be found in a corporate environment where selective restrictions may exist on some, but not all, devices such as stations. An executive, for example, may be permitted access to a call forwarding feature while a non-executive is not permitted such access. Non-executives are restricted because excessive call fowarding is burdensome to the operation of the PBX. Therefore, each non-executive station is assigned a restriction which prohibits call forwarding. Circumventing the restriction burdens the operation of the PBX.
The PBX or communication system also provides well defined call establishment capabilities. Each cell establishment operation conforms to a precribed set of conventional conditions. If the conventional conditions are not met, then "atypical" call establishment conditions exist. Atypical conditions often indicate either communication device or facility misuse, communication device or facility failure or improper or unauthorized PBX user activity.
An example of typical vs atypical conditions is described with respect to the operation of dialing from a device such as a station. A calling party, typically, makes one or two call attempts to reach other PBX stations over some specified period of time, e.g. two call attempts per hour. However, if a calling party utilizes an electronic automatic dialer, the number of attempts and the speed at which attempts are made increase dramatically over the specified period of time, e.g. 60 call attempts or more per hour. In the latter case, the call establishment conditions are atypical. The existence of the atypical condition may be indicative of improper PBX operation or unauthorized PBX user activity. For example, an automatic dialer is sometimes used to find a computer access number to gain unauthorized access to a computer data bank.
Another example of typical vs atypical conditions is described with respect to the length of time a trunk remains busy. Typically, a trunk remains busy for some expected duration of time, e.g. 40 minutes. However, the existence of a trunk busy condition for 24 hours is atypical. The presence of this atypical condition may indicate that a user is attempting to "tie-up" the trunk facilities. The presence of this condition may also indicate that a station's receiver was accidentally knocked "off-hook". This atypical condition indicates either device or facility misuse or failure.
The above-cited examples of restriction tampering and device or trunk facility misuse, failure, or unauthorized or improper PBX user activity are clearly the type of activities or occurrences that should advantageously be made known to a PBX administrator. It would also be advantageous if such activities or occurrences could be easily and immediately detected so that appropriate remedial action could be taken. Heretofore, no such method existed for addressing the above-cited considerations and problems with respect to accessing PBX features or detecting the occurrence of atypical PBX call establishment conditions.